1. Field of the Invention
The present invention, called a "brain stethoscope", relates to a medical apparatus and more particularly to a portable EEG (electroencephalograph) device to detect, amplify and analyze brain waves generated by a human and to transmit the results to a remote receiver.
2. Related Art
It has become evident that human brain electrical activity is precisely regulated by a complex brain homeostatic system. Normative values are precisely predictable and have been found to be independent of ethnic factors. Characteristic patterns of deviation from such normative values have been reported for a wide variety of developmental, neurological and psychiatric disorders.
At the present time it is difficult for emergency personnel to determine if a subject has suffered injury to the brain or the spinal cord, cerebrovascular obstruction (stroke) or hemorrhage (bleeding). If these conditions could immediately be identified, patients' lives may be saved through rapid and appropriate treatment, usually determined after a subsequent neurological exam. The causes of abnormal behavior such as violent outbursts are often similarly ambiguous.
It is usual, during a routine medical examination, to evaluate the heart using an EKG (electrocardiogram) device. Usually, there is no attempt to determine if the patient has any brain dysfunction or conditions that may be discoverable using an EEG (electroencephalograph), as generally such devices produce an analog wavy set of waveshape tracings which must be interpreted subjectively by skilled electroencephalographers. Consequently, although the patient may be suffering from brain damage or dysfunction, such as a tumor, it is often not detected in the course of the medical examination. The absence of information about central nervous system (CNS) dysfunction often results in suboptimal treatment.
As an example, a patient arrives at a hospital emergency room (ER) with certain physical symptoms of ischemic stroke, or "brain attack", resulting from blocked blood flow to the brain. Unless the patient is treated promptly, brain cells in the ischemic region would continue to be deprived of oxygen, possibly destroying parts of his cognitive abilities, memory and motor skills and possibly resulting in death. Such adverse effects of ischemic stroke may be halted by immediate and appropriate treatment, for example, injection of tissue plasminogen actuator (tPA), which dissolves clots. However, tPA treatment of a possible stroke victim may be hazardous to initiate, as his physical symptoms may be caused by an intracerebral hemorrhage which can be worsened by dissolving clots. Quantitative analysis of the EEG (QEEG) may provide a rapid and objective diagnosis between these alternatives.
As another example, a person may be in a coma when emergency ambulance personnel (EMS) arrive. He should not be moved if he has suffered spinal injury. But the ambulance personnel cannot determine if he has suffered spinal injury by simply looking at the comatose patient. Somatosensory evoked potentials (SEPS) provide assessment of the functional integrity of the spinal cord.
Another example of the need for an objective and immediate brain assessment is in situations where there are a number of injured persons who may require medical attention, some of whom may be in a coma. For example, on the battlefield or in the event of a train wreck, it may be necessary to separate comatose patients who are breathing and viable and require immediate treatment, from those who are still breathing but are brain dead. And again, in that situation, it is important to tell if a patient who is comatose but alive has a spinal injury, so that he should not be moved. QEEG, SEPs and brainstem auditory evoked response (BAERs) may provide a rational basis for triage in such situations.
A series of publications and patents in the name of Dr. E. Roy John relate to the field of EEG "neurometrics", which is quantitative electrophysiological measurements (QEEG) evaluated relative to normative data. Generally, a subject's analog brain waves, at the microvolt level, are amplified, artifacts removed and the amplified brain waves converted to digital data. That data is then analyzed in a computer system to extract numerical descriptors which are compared to a set of norms (reference values), either the subject's own prior data (initial state) or a group of normal subjects of the same age (population norm). Such analyses can quantify the level, if any, of deviation of the activity of any brain region from the reference values.
A computer system based instrument using those principles is the "Spectrum 32" (Cadwell Instruments, Washington). That instrument is large, non-portable and relatively expensive (tens of thousands of dollars). It is generally used by experienced neurologists in a neurology clinic or hospital neurology department. It is not suitable for use in an ambulance, emergency room or a doctor's office for regular medical examinations. Some of the aforementioned patents which relate to neurometrics are U.S. Pat. Nos. 4,279,258; 4,846,190; 4,913,160; 5,083,571 and 5,287,859, incorporated by reference.
There are a number of patents directed to determine whether a person is alive. For example, Allain U.S. Pat. No. 5,029,590 discloses the use of a pocket-size monitor for life detection. The Allain patent deals primarily with detecting heartbeat via EKG and mentions detecting brain waves using EEG.
In John U.S. Pat. No. 3,706,308 entitled "Life Detecting Medical Instrument" a portable device has EKG and EEG monitors, a stimulator for evoked brain responses (Evoked Potential--EP), an average response computer and a visual display. It determines if a patient is legally dead by comparison of the patient's brain waves with predetermined standards of brain death and does not use comparisons with normal values.
There is an existing need for a portable self-evaluating EEG and EP device which can be monitored by a hand-held control distant from the patient. For example, where an injured person's heartbeat cannot be detected or he is in a coma, he may be taken to a hospital, which has an EEG device and neurologist to detect and evaluate brain waves and to determine whether he is alive and whether his brain is injured. However, in some emergencies, medical personnel need to quickly determine if a patient has had a stroke or if the patient is alive but in a coma, or dead, or if a person has suffered spinal injury. A particular difficulty arises when some patients have spinal injury and are unconscious. In those cases, it would be difficult for medical personnel to ascertain who can safely be moved or should not be moved because of spinal injury. Persons with such conditions may die due to the lack of medical information, for example, a non-spinal injury patient may be in a coma and is not properly and timely transported to a hospital, or may become paralyzed if moved with unrecognized spinal injury.
In general, there are numerous instances in which the ability to make a "brain scan" by a portable EEG/EP device ("Brain Stethoscope") could be valuable in assessing the probability of abnormal brain function rapidly and automatically.